OK, smaller jibs for light air and for 'pointing' ........

[RichH]

The problem is I only have ONE BIG LP headsail. :-O


Is there any 'improvement' for my dilemma with a tight budget????



Yes indeed! not 'perfect nor best' but can 'help' for when sailing in 'super-light', etc. winds.

Some 'suggested experiments/trials' ... and you be the judge if it improves your sailing/pointing in 'super light' conditions. (record what you do so it can be repeated)

1. if you have a furler/reefing arrangement, try/experiment to partly furl the headsail a bit. Even that you will increase 'turbulence' due to the increased 'roll on the foil' at the luff, you will be reducing LP, and you will be rolling up the area of the sail that has its 'broad-seaming' - seams near the luff that are 'tapered' by cutting away smooth curves from the edges of the panels to be assembled... with the broad-seamed area now partly (and tightly) rolled up on the foil, the sail becomes 'flatter' and with less draft.

2. Experiment with the "Slot Open distance".
The higher the wind speed the more the 'slot' should be 'opened' (outboard); conversely, the lower the wind speeds the less the 'slot open' distance should be. For 'perfect' trim there is only one correct 'slot open distance' ... and its set by the amount of wind speed in the 'slot'.
How do I know how far in nor out?
method:
1. Set up sail shape and trim as best as possible while watching the full set of telltales.
2. Go onto a hard beat, and while watching the lower luff of the mainsail pull in on the 'barberhauler' (can be a simple loop of rope attached horizontal to the deck plane of the boat at near 90° to boats centerline and attached to the clew or jibsheet) .... pull in until you start to see what looks like 'backwinding' starting to show up ... release the barberhauler a wee bit in increments as you watch the speedo or VMG for 'maximum'.
A better way to do this is watch the bottom and 'next higher' tell tales at near mid-cord on the leeside of the main ... pull in until the bottom and next-up mid-cord tell tale becomes 'agitated', then release the b-hauler an inch or two, while watching for MAXIMUM out of the speedo/VMG.... and then re-correct jib 'shape' for the proper flow of the tell tales (on both main and jib) with the barberhauler being used.
2a. FWIW - When in High Winds .... watch the distance between the jib leach and the spreader tip (racers mark the underside of the spreader with incremental marks an inch or two apart so that they can better estimate the 'distance off' .... and then release tension on the jibsheet a bit to allow the clew to go 'outboard' while watching the speed or VMG ... the speedo will tell you when its correct.

3. If the sail is so large in LP that its leech is touching or fouling on a spreader when the clew is 'barberhauled', simply furl the sail until its no longer touching the spreader, etc. if its 'best' clew in/out position is much 'inside the rail', when 'barberhauling'.

The end goal of all these suggestions is to sail FASTER in super-light winds so that you can 'make' your own 'apparent wind'.

Note: if you have a 'heavy boom' whose weight is making the sail's leech 'too tight' and/or the boom weight is causing the leech to 'hook up to the weather side', or the jib leech is not of the same apparent shape/curve of the mainsail leech .... add some topping lift pressure to counteract the weight of the boom, or release some down-force from your 'rigid' boom vang.

Your comments/contributions are appreciated.

 

[356_Steve]

Re: OK, smaller jibs for light air and for 'pointing' ......

Rich...

I have two jibs, the 110 that came with the boat, and a 155 that I added. WIth the 110, there is next to no slot, and I have never got the boat to move in less than 3-1/2 knots of air. As I noted in the posted question, I can get the boat moving up to and a little beyond true air with the 155 in 1-1/2 to 2 knots or air. There are times that I have completely furled the headsail and then let the main out half way to the spreaders to stop the boat from boxing the compass, but once I have some headway and start pointing, I let out the jib fully to get the slot and the speed comes up.

Question on all this...does the small jib apply when the main vice the jib is the power sail on the boat? I have noticed that I have to adjust some of Don's sail trim on the Hunters with the large roach main, swept back spreaders, and no backstay.

 

[RichH]

A. WIth the 110, there is next to no slot,

B. Question on all this...does the small jib apply when the main vice the jib is the power sail on the boat? I have noticed that I have to adjust some of Don's sail trim on the Hunters with the large roach main, swept back spreaders, and no backstay.

A. the 356 has its fairlead / genoa track on top of the coach roof and well inboard of the rail. Indeed if see I this correctly there will be little room for the slot to even exist on just about all jib/genoas, and suspect that to really get your boat 'moving' that you probably now have to have the jibsheets quite slack as perhaps if the jib sheets are 'real tight' you either easily 'backwind' or you fall off into a very high reach from being well close hauled? The main HAS to be flattened down in almost all wind conditions ... or the backwind can be often and 'tremendous' especially low down and near the mains tack, correct?

Try/test this. draw an imaginary line emanating from the tack fitting and at an angle from the centerline at 10° and one 12°
With a J dimension of 13.2ft (tack to face of mast) or 158" ... those imaginary lines should 'fall across' at a place exactly 27" (10°) and 31"(12°) perpendicular and away from the centerline at the mast base ....... WOW thats a quite narrow slot distance, especially for the 110 (~300 sq. ft), the 155 will have a lot of more of total camber and thus will be a bit further away ... at the mast. Whats happening here maybe that due to the too-close-to-the-centerline genoa track on that coach roof, the 'tack to clew angle' may be well less than the normal 10-12°. I 'think' increasing the jib tack to clew line to 12°+, or slightly more, will be the direction you will have to consider; normal tack to clew is usually 10° by most boat designers, 12° if the boat is 'heavy'.

If you dont have a 'full' set of tell tales' including a 'row of steering tell tales' (3-4 small length tell tales all in a row & starting from the luff then back, and about 'eyeball level' up from the tack) on this 110%, Id start there. Then follow Don's Sail Trim Guide to be sure of 'the basics'.

More .... consider to do a Rube Goldberg barberhauler and do some trials to take the clew more 'outboard' and at a jib angle of more than that 10-12° and see if this doesnt pick up the speed and 'performance' for both sails. Also, If youre not a member of the 356 owners group, consider to join, and then ask someone who is successfully racing this boat to comment on what they did to improve on this quite narrow slot distance and what did they do that 'worked' other than to sail with 'well eased' or 'slack' jibsheets .....or using 'simultaneously and in 'bridle fashion' the coach roof track AND a track on the RAIL.
There are other possibilities for correction, but lets not think about recutting sails at this point, ;-o

Please let the group know how this turn out.


B. Power and the effects of sail efficiency doesnt come from one sail in any 2-sail combo. Such comes from the 'correct' sail interaction between the 2 sails. Good jib shape and trim enhances the output of the main; and, good main shape and trim enhances the output of the jib. This combo or 'interaction' of the two sails together is what make the jib/main combo 'work'.
Only when one sail of two set 'combo' becomes 'ridiculously' small and the other grossly large in comparison (current AC boats) does one sail 'dominate' over the other.

 

[oday630]

I have what is I guess a storm sail for my Oday 28. The sail came with the boat so not sure if was made for this boat or just modified to fit. The luff on this sail is about 36" shorter than normal, but has a wire that extends from the tack to make up the distance. I was wanting to experiment with this sail on these light wind days. Should I take the wire off and put the tack as close to the deck as possible or keep the sail up high? I'm not sure if the added sail area aloft would help or hurt.

 

[oday630]

Just to add, the sail is probably a 90%-100%. Can't really remember I've only had it out once.

 

[RichH]

Re: OK, smaller jibs for light air and for 'pointing' ......

Getting the clew and foot as close to the deck as possible will tend to prevent 'shunting' of air flow from the high pressure side to the low pressure side (which also then causes to form a parasitic 'rotor' following the sail). Getting the sail as close to the deck as possible would equate to putting 'winglets' along the foot to increase sail (aircraft wing) performance.

(Someone ultimately is going to put winglets at the top of the sail too .... birds 'do it', by 'fanning out' their primary feathers which is more efficient than winglets, so you may see someday someone with 'feathers' at the top and bottom of sails :-o)

 

[oday630]

Thank you! I will move the wire "pendant" to the top and give it a try. Not the feathers though. I'll let someone else try that.

 

[356_Steve]

A. the 356 has its fairlead / genoa track on top of the coach roof and well inboard of the rail. Indeed if see I this correctly there will be little room for the slot to even exist on just about all jib/genoas, and suspect that to really get your boat 'moving' that you probably now have to have the jibsheets quite slack as perhaps if the jib sheets are 'real tight' you either easily 'backwind' or you fall off into a very high reach from being well close hauled? The main HAS to be flattened down in almost all wind conditions ... or the backwind can be often and 'tremendous' especially low down and near the mains tack, correct?

Try/test this. draw an imaginary line emanating from the tack fitting and at an angle from the centerline at 10° and one 12°
With a J dimension of 13.2ft (tack to face of mast) or 158" ... those imaginary lines should 'fall across' at a place exactly 27" (10°) and 31"(12°) perpendicular and away from the centerline at the mast base ....... WOW thats a quite narrow slot distance, especially for the 110 (~300 sq. ft), the 155 will have a lot of more of total camber and thus will be a bit further away ... at the mast. Whats happening here maybe that due to the too-close-to-the-centerline genoa track on that coach roof, the 'tack to clew angle' may be well less than the normal 10-12°. I 'think' increasing the jib tack to clew line to 12°+, or slightly more, will be the direction you will have to consider; normal tack to clew is usually 10° by most boat designers, 12° if the boat is 'heavy'.

If you dont have a 'full' set of tell tales' including a 'row of steering tell tales' (3-4 small length tell tales all in a row & starting from the luff then back, and about 'eyeball level' up from the tack) on this 110%, Id start there. Then follow Don's Sail Trim Guide to be sure of 'the basics'.

More .... consider to do a Rube Goldberg barberhauler and do some trials to take the clew more 'outboard' and at a jib angle of more than that 10-12° and see if this doesnt pick up the speed and 'performance' for both sails. Also, If youre not a member of the 356 owners group, consider to join, and then ask someone who is successfully racing this boat to comment on what they did to improve on this quite narrow slot distance and what did they do that 'worked' other than to sail with 'well eased' or 'slack' jibsheets .....or using 'simultaneously and in 'bridle fashion' the coach roof track AND a track on the RAIL.
There are other possibilities for correction, but lets not think about recutting sails at this point, ;-o

Please let the group know how this turn out.


B. Power and the effects of sail efficiency doesnt come from one sail in any 2-sail combo. Such comes from the 'correct' sail interaction between the 2 sails. Good jib shape and trim enhances the output of the main; and, good main shape and trim enhances the output of the jib. This combo or 'interaction' of the two sails together is what make the jib/main combo 'work'.
Only when one sail of two set 'combo' becomes 'ridiculously' small and the other grossly large in comparison (current AC boats) does one sail 'dominate' over the other.

Rich,

I had a low air race today, and tried furling the 155 down to about a 120, and ran the lee sheet to the coach roof track. This gave me a sheet to pull the sail down from the coach, and out via the sheet from my out board track. The result was that the boat slowed by over 1/2 knot...I could not sail faster that true wind speed no matter how I adjusted the trim.

Using the 155, I could sail close hauled faster than true wind (2 to 2-1/2 knots) by adding in boat speed, resulting in about 3 to 3-1/2 knots SOG. I was sailing as high or higher than boats around me, and also sailing faster.

Perhaps it might be the cut of the sails on the 356? The jibs about 2' off the deck to clear the lifelines, and to compensate for the coach roof track. I have found that I can pretty much sail as fast and as tight in med air as other boats in my class (Ericson 35's, Catalina 34's) using the 155, but cannot keep up using the 110. In heavy air, a reef in the main with the 110 allows me to walk away from them until we head down wind.

Steve

 

[RichH]

Re: OK, smaller jibs for light air and for 'pointing' ......

Steve
as for the 356 with that narrow slot distance, youre definitely going to have to do some 'trials' to find where the boat optimizes with any choice of jib/genoa. Thats why I offered how to check for that 10-12° jib tack to clew line as a reference.
Make two temporary marks on your coachroof at a spot 27 inches and/or 31 inches at 90 degrees from the front of the mast towards the side. Take a 'rope' and pull tight between the forestay wire (tack of the sail) to your 'normal' position of the fairlead car. If the 'line' is outboard of these marks - OK. If that 'line' is inside between the mark and the mast, then barberhauling to take the clew outboard is usually indicated.

Why I state to do trials, especially when 'partly furling' is that the partial 'roll-up' on the foil 'may' be causing more turbulence and/or causing a separation stall AT the luff; and, such is quite 'detractive' from developed power. For light winds, the leading edge shape should be quite flat, something that is near impossible when the furler has a 'rolled up sail' on it. The thicker the 'roll-up' the worse it will be. From your trials, the 'numbers' (VMG or speed vs. time to your 'mark') that you develop/record will tell you which way is best or not.
As I stated previously your boat has a very close slot distance, and if the slot open distance is 'too tight' (or too open), sail efficiency and sail interaction can drastically fall off.

;-)

 

[356_Steve]

Re: OK, smaller jibs for light air and for 'pointing' ......

Rich,

I will keep playing with it. I did have the jib rolled tight, but I think with it so high above the deck that it may not make it feasible. I will give the measurements a look, and even play with the 110 when not in a race at some point. However, switching to the factory 110 won't work because I get smoked going downwind then. I may have to settle for doing as well as other boats upwind and then leaving them behind on the other legs.

Steve